Communication system and filter thereof

Abstract

The invention discloses a communication system and a filter thereof. The filter comprises: a first port, a second port and a first common cavity connected with the first port, which are arranged on a shell; a first filtering branch coupled with the first port and composed of ten filtering cavities which are coupled in sequence, wherein the ten filtering cavities of the first filtering branch further form five cross coupling zero points; a second filtering branch respectively coupled with the first common cavity and the second port and consisting of eight filtering cavities which are sequentially coupled, wherein the eight filtering cavities of the second filtering branch further form three cross coupling zero points; and a third filtering branch respectively coupled with the first common cavity and the second port and consisting of five filtering cavities which are sequentially coupled, wherein the five filtering cavities of the third filtering branch further form two cross coupling zero points. Through the above mode, the arrangement of the common cavity and the common port can reduce the number of taps and reduce the size of the filter, the cross coupling zero point can realize zero point suppression, and index debugging is facilitated.

Description

technical field [0001] The present application relates to the technical field of communication, in particular to a communication system and a filter thereof. Background technique [0002] In the mobile communication system, the required signal is modulated to form a modulated signal, which is carried on a high-frequency carrier signal, transmitted to the air through the transmitting antenna, and the signal in the air is received through the receiving antenna. Among the signals received by the receiving antenna, not only Include the desired signal, but also include other frequency harmonics, noise signals. For the signal received by the receiving antenna, it is necessary to use a filter to filter out unnecessary harmonics and noise signals. Therefore, the designed filter must precisely control its bandwidth. [0003] The inventors of the present application found in long-term research and development work that in order to reduce the volume of the filter, the filter is usual...

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Problems solved by technology

[0004] This application provides a filter to solve the problem that the number of filter taps in the prior art is too large, resulting in more welding points required, poor performance such as out-of-band suppression, and it is difficult to achieve filtering branches of different frequencies Technical issues with a high degree of isolation between

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